Just pick one. Appimage fits the bill quite nicely and does not depend on a certain distribution. It's drop and forget. No silly mounts or other "infrastructure" needed to deploy.

I haven't used Flatpak but Snap is quite annoying and it was one of the reasons I switched from Ubuntu to Debian. Even if you unininstall snapd in Ubuntu 18 you are still stuck with the annoying mount points. That and the auto-updates.